The present invention relates to an internal combustion engine for use in a vehicle powertrain, and more particularly, to a double displacement engine having first and second crank shaft portions selectively coupled to one another by a fluid lock such as a torque converter.
Internal combustion engines have been used for many years for providing motive power for driving a vehicle. Most vehicles on the road today are provided with either a four, six, or eight cylinder engine which is selected based upon the typical torque demand requirements for the individual type vehicle being designed. For example, four cylinder engines are typically used for commuter vehicles which are compact and typically have low load requirements and limited performance expectations. Six cylinder and eight cylinder engines are typically employed in larger vehicles wherein larger load carrying capacity and higher performance are expected. Some of the existing vehicle designs have suffered from the deficiency that the internal combustion engine for the vehicle has to be designed with a larger capacity than is most often required for optimal fuel efficiency.
The dual displacement engine of the present invention overcomes these deficiencies by providing a powertrain system that includes a dual crank shaft system with one of the crank shaft systems being independently operable for providing driving torque to a transmission while the second crank shaft system can be utilized to supplement the driving torque of the first crank shaft system to meet higher torque demand requirements. Operation of the first and second crank shaft systems is provided such that during normal driving at constant speeds and typical driving loads, the first engine crankshaft system is utilized for providing driving torque to the wheels of the vehicle. During periods of operation where increased levels of torque are required, such as during acceleration, pulling a heavy load, or climbing a hill, a torque converter or other fluid coupling-type device can be engaged in order to provide a connection between the first and second crankshaft systems for starting up and thereby operating the second crankshaft system in conjunction with the first crankshaft system for meeting the higher torque demand requirements.